Refactor SignalR client DI and config, add test factory
Refactored FruitBankSignalRClient construction to use DI and centralized configuration from appsettings.json across all platforms. Introduced TestSignalRClientFactory for consistent test setup. Added FruitBankHubConnectionExtensions for reusable SignalR connection and logging configuration. Updated Program.cs and MauiProgram.cs to register logger factories, log writers, and IHubConnectionBuilder via DI. Embedded appsettings.json in MAUI and updated .csproj references for build flexibility. No business logic changes; all updates are infrastructure and test setup.
Refactored `OnDataSourceLoaded` to be asynchronous for better state handling. Downgraded `Newtonsoft.Json` to version `13.0.3` across multiple projects for compatibility. Enhanced `MeasuringItemPalletBase` with `SetParentPropToNull` and `SetForeignKey` methods. Refactored `OrderItemPallet`, `ShippingItemPallet`, and `StockTakingItemPallet` to simplify table attributes and improve parent-child relationship handling.
Added `IsReadyForClose` to `StockTaking` for better closure validation. Updated SignalR tag constants to reflect new functionality. Improved Razor components (`PalletItemComponent`, `StockTakingTemplate`, `MeasuringIn`, `MeasuringOut`) to streamline logic and maintain proper references.
Introduced `JsonExtensionTests` for comprehensive validation of JSON serialization/deserialization, including deep hierarchies, circular references, and hybrid references. Added `test_debug.ps1` for streamlined test debugging. Performed general code cleanup and improved test coverage.
Loretta